Alternate-current motor.



V. A. FYNN. ALTERNATE CURRENT MOTOR.

APPLICATION FILED MAY 26, 1910.

Patented Jan. 14, 1913.

2 SHEETSSHEET 1.

nvvmoa Valere A. Fynn WITNESSES:

V. A. PYNN. ALTERNATE CURRENT MOTOR. APPLICATION FILED MAY 26, 1910.

Patented Jan. 14,1913.

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WITNESSES: INVENTOR Valre A. Fynn.

-..m.w1; BE 2 omvirs STATES PATENT OFFICE.

VALERE ALFRED FYN N, 0]? LONDON, ENGLAND.

ALTERNATE-CURRENT MOTOR.

To all whom it may concern:

Be it known that I, VALiiRE ALFRED FYNN, a subject of the King ofEngland, residing at London, England, have invented a certain new anduseful AlternateCurrent Motor, of which the following is such a full,clear, and exact description as will enable any one skilled in the artto which it appertains to make and use the same, reference being had tothe accompanying drawings, forming part of this specification. Myinvention relates more particularly to single phase alternate currentinduction motors having a permanently shortcircuitcd induced member,such as a squirrel-cage, or to such motors having an induced windingadapted to be permanently short-circuited by means of slip rings or insome like manner.

The principal object of my invention is to cause such single phasemotors to start with a powerful torque without the use of a commutator.I achieve this object in my preferred form of motorby providing theinduced member with a plurality of polyphase windings closed onthemselves, either directly or over resistance; by separating at leasttwo of such windings by a magnetic bridge or shunt; by providing atleast two angularl displaced windings on the inducing mem er; byarranging one of said windings in good inductive relation with theinduced member and by arranging the other of said windings in poorinductive relation with the induced memben.

My invention and its several advantages will be better understood byreference to the following description, taken in connection with theaccompanying diagrammatic drawings of two-pole motors in which Figure lis a diagrammatic representation of my improved motor showing series0011- nections between the stator windings; Fig. 2 is another suchdiagram showing shunt connections between the stator windings; Fig. 3shows the preferred arrangement of slots in rotor and stator; Fig. 4illustrates the preferred arrangement of rotor winddings in a rotorslot; Fig. 5 shows a modi fied arrangement of rotor slots and Fig. 6 isa cross-section through the active material of a complete motor.

Referring to Fig. 1, the rotor 19 is by way of example provided witheight slots 24 carrying two windings 21 and 22 either per- Specificationof Letters Patent.

Patented Jan. 14, 1913.

Application filed May 26, 1910. Serial No. 563,540.

which may consistof solid or laminated iron or steel. The arrangement ofthese windings with a solid magnetic bridge in one and the same slot isshown to a larger scale in Fig. 1. In Fig. 5 is shown one way ofseparating the windings 21 and 22 by a laminated magnetic bridge. Tothis end, winding 21 of Fig. 5 is placed in open slots 34 situated nearthe rotor periphery and winding 22 is placed in closed slots 35 placedsome distance away from the rotor periphery and so as to leave amagnetic bridge 23 between the two windings. The bridge more fullyillustrated in Fig. 4; is inductively responsive to any flux threadingit because such flux can set up Foucault currents therein. I prefer tomake use of an inductively responsive magnetic bridge or shunt. Thewindings 21 and 22 are shown in their preferred squirrel-cage form inFig. 6. I prefer to give 21 a higher resistance than 22. The stator ofthe motor shown in Fig. l carries two windings 17 and 18 displaced by p90 electrical degrees and connected in series relation. This seriesrelation is here ob tained by means of a series transformer 34adjustable at 35 and 36. It is well understood that this seriestransformer can often be dispensed with when the two windings would bedirectly connected in series with each other. The winding 18 is intendedto be placed in the best possible inductive relation with the outerrotor winding 21; in order to indicate this diagrammatically in Fig. 1the winding 18 has been shown much wider than 17 which is intended to beplaced in poor inductive relation with 21. These requirements can befulfilled in practice for instance by distributing winding 18 into manyopen stator slots per pole and by bunching winding 17 into very few oreven into only one' slot per pole. If desired, the slot or slotscarrying 17 can in addition be set back from the stator bore. Such anarrangement is shown in Fig. 3 where 18 is distributed in the open slots3, 4: 16 and where 17 is bunched into the closed slots 1, 2 set backfrom the stator bore. The number of turns of winding 17 of Fig. 1 can bevaried by means of switch 28, the direction of the magnetizationproduced by 17 relatively to that produced by 18 can be changed by meansof the reversing switch 27. Switch 28 thus controls the magnitude of thestarting torque while switch 27 controls the direction of rotation.

The starting performance can often be im proved by adjusting the phaseof the current in 17 relatively to the phase of the current in 18. Oneway of doing this is shown in Fig. 1 where a resistance 29 adapted to beregulated at 30 is connected in parallel with 17 Thls resistance mayalso be said to vary the phase of the E. M. F. at the terminals of 18with respect to the phase of the F.

at the terminals of 17 The machine will start in the one or otherdirection, according to the position of 27, as soon as the motor isconnected to the .mains 25, 26. The turns of 17 and the value of theresistance 29 may be adjusted as the speed increases and 17 and 29 maybe entirely out out when a suflicient speed has been reached, yet it isnot necessary to cut out 17. I have discovered that when the two stat-orwindings are connected in series relation the machine shows the markedadvantage of a torque which steadily increases with increasing speeduntil the maximum is reached at a speed value in the neighborhood ofsynchronism. The operation of the machine in its series connection issuificiently good to permit in some cases the use of only one rotorwinding.

In, Fig. 2 the stator windings 17 and 18 are connected in parallelotherwise the details of constructionare supposed to be the same as.described with reference to Figs. 3, 1, 5 and 6 in connection with Fig.1.

The starting performance can often be improved by adjusting the phase ofthe current in 17 relatively to the phase of the current in 18 or byadjusting the phase of the E. M. F. at the terminals of 17 relatively tothe phase of the E. M. F. at the terminals of 18. One way of doing thisis shown in Fig. 2 where an inductive resistance 31, regulatable at 32is in circuit with 18 while an ohmic resistance 29 regulatable at 30 isin circuit with 17. The direction of rotation can be reversed byreversing the current through one of the stator windings, for instancethrough 17 by means of the reversing switch 27. The magnitude of thetorque can be varied by adjusting 29, 31 or the number of turns in 17. Iprefer to interrupt the circuit containing 17 and to cut 31 out ofcircuit after the motor has reached a suflicient speed but the machinecan be op-v erated with both stator windings in circuit.

Referring to the operation of the machine, winding 18 induces theworking current in the rotor windings and the winding 17 produces theflux which is mainly responsible for the torque in conjunction with theworlo ing current. The flux due to 17 can be made large without inducingmuch current in the rotor windings owing to the poor inductive relationbetween 17 and 21 and the still poorer inductive relation between 17 and22. As the motor gathers speed the short-circuited rotor winding orwindings set up a motor field in the usual way and the efiect of thewinding 17 automatically becomes of secondary importance, the motorgradually acquiring the well known characteristics of a self-excitedshunt induction motor.

Having fully described my invention, what I claim as new and desire tosecure by Letters Patent of the UnitedStates, is:

1.'In an alternating current motor, the combination with an inducedmember having two windings and a magnetic bridge or shunt separatingsaid windings, of an 1nducing member provided with two axially displacedwindings oneof said windings being placed in better inductive relationto the induced member than the other winding.

2. In an alternating current motor, the combination with an inducedmember having two windings and an inductively responsive magnetic bridgeor shunt separating said windings, of an inducing member provided withtwo axially displaced windings one of said windings being placed 1nbetter inductive relation to the induced member than the other winding.

3. In an alternating current motor, the combination with an inducedmember having two windings and a'magnetic br1dge or shunt separatingsaid wind ngs, of an mducing member provided w1th tw o axially displacedwimlings, one of said w1nd1ngs being placed in better inductive relationto the induced member than the other winding,

and means for controlling the relative phase of the currents in the twowindings on the inducing member.

4. ln an alternating current motor. the combination with an inducingmember provided with a maiuinducing winding and a field winding axiallydisplaced therefrom and disposed in fewer slots per pole than the maininducing winding, of an induced member having two windings and amagnetic bridge or shunt separating said two windings.

5. In an alternating current motor, the combination with an inducingmember provided with a main inducing winding and a field winding axiallydisplaced therefrom and disposed in fewer slots per pole than the maininducing winding, of an induced memher having two windings, a magneticbridge or shunt separating said windings, and means for controlling thephase relation of the magnetizations due to the field winding and themain inducing winding.

6. In an alternating current motor, the combination with an inducingmember provided with a main inducing winding disposed in a plurality ofslots per pole and a field winding displaced therefrom and disposed inone slot per pole, of an induced memberhaving two windings, and amagnetic bridge or shunt separating saidwindings.

duced member having two permanently short-ci'rcuited windings, amagnetic bridge or shunt separating said windings, and means forcontrolling the phase relation of the potentials impressed on the maininducingand the field windings.

. 8..In an alternating current motor, the

combination with an inducing member provided with a main inducingwinding and a field winding displaced therefrom and disposed in closedslots, of an induced member having two windings and a magnetic bridge orshunt separating said windings.

9. In an alternating current motor, the combination with an inducedmember provided with a polyphase winding, of an inducing member providedwith a main inducing winding and a field winding axially displacedtherefrom and connected in series re lation therewith, said inducingwinding being placed in better inductive relation to the induced memberthan said field winding.

10. In an alternating current motor, the combination with an inducedmember provided with a'polyphase winding, of'an inducing member providedwith a main inducing Winding and a field winding axially displacedtherefrom and connected in series relation therewith, said field windingbeing disposed in fewer slots per pole than said main inducing winding,and means for controlling the phase relation of the po tentialsimpressed on the main winding and on the field winding.

11. In an alternating current motor, the combination with an inducingmember provided with a main inducing winding and a. field windingaxially displaced therefrom and connected in series relation therewith,said-field winding being disposed in fewer slots per pole than said maininducing winding, of an induced member carrying two permanentlyshort-circuited windings, and a magnetic bridge or shunt separating saidwindings.

12. In an alternating current motor, the combination with an inducingmember provided with a main inducing winding and a field winding axiallydisplaced therefrom and connected in series relation therewith, saidfield winding being disposed in fewer slots per pole than said maininducing winding, of a laminated induced member carrying two permanentlyshort-circuited windings, and a magnetic bridge or shunt separatinginducing at least one element whose dimension in a direction parallel tothe motor shaft is greater than the thickness of the laminations of theinduced member.

said windings, said magnetic bridge having 13. In an alternating currentmotor, the

combination with an induced member provided with a polyphase winding, ofan inducing member provided with a main in-:

ducing winding disposed in open slots and a field winding axiallydisplaced therefrom and connected in series relation therewith, sizidfield winding being disposed in closed s ots. f

In testimony whereof, I have hereunto set my hand and afiixed my seal inthe presence of two subscribing witnesses.

VALERE ALFRED .FYNN. a 5.

Witnesses:

E. E. HUFFMAN, ELIZABETH BAILEY.

